JPH05283230A - Nonmagnetic board for magnetic head - Google Patents

Abstract

PURPOSE:To obtain a nonmagnetic board for a nonmagnetic magnetic head in which a metallic magnetic film is vapor-deposited. CONSTITUTION:A nonmagnetic board for a magnetic head contains CoO and NiO as a basic composition and 0.1-10wt.% of MgO is added to the composition. The board of this composition can obtain substantially equivalent characteristics in both thermal expansion rate and hardness to those of a magnetic film structure. Thus, peeling, cracks of the structure can be significantly prevented. Further, its hardness is enhanced thereby to suppress shortening of a life of the head, deformation, cracks, etc., of the board, and its wear resistance, durability of the head are particularly excellent as its advantages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic substrate for a non-magnetic magnetic head for depositing a metallic magnetic film.

[0002]

2. Description of the Related Art Barium titanate, calcium titanate, alumina, etc. have hitherto been used for such applications. However, since the coefficient of thermal expansion was largely different from that of the magnetic film structure, the vapor-deposited magnetic film structure was easily peeled off, and stress was generated due to the difference in the coefficient of thermal expansion, and cracks were sometimes generated.

Further, conventional materials for non-magnetic substrates have low hardness, and particularly when a high coercive force tape (so-called metal tape) is used as a magnetic recording medium, a magnetic film structure (hardness Hv = 600 to 800). ) And sliding and friction with a magnetic tape having different hardness and wear resistance cause uneven wear on the non-magnetic substrate, resulting in a change in the magnetic characteristics of the magnetic film structure. In particular, when the hardness of the non-magnetic substrate is low, the uneven wear of the magnetic film structure is remarkable, the life of the magnetic head is shortened, and the defects such as deformation, cracking and peeling of the non-magnetic substrate are remarkable. It was

The present inventors have advanced research on oxide-based ceramics in order to solve the above-mentioned drawbacks, and have conducted research on CoO and Ni.
Oxide having a basic composition of O or NiO is already effective, and its composition has already been disclosed in Japanese Patent Laid-Open No. 1-287811.
JP-A-2-168602 and JP-A-3-08041
No. 2 discloses the composition of the non-magnetic substrate. In addition, we examined additives to improve hardness and density, and
O, NiO as a basic composition, MnO, TiO ₂ , Al
Composition containing 0.1 to 5 wt% of one or more of ₂ O ₃ and CaO, and 1 to 5 wt% of Y ₂ O ₃ , 0.1 to 1%
Of TiN and 0.3 to ₂ wt% of B ₂ O ₃ added at least one kind or 1 to 5 wt% of SiO ₂ is effective as a magnetic head substrate and the additive is expected. It was confirmed that the above effects were exhibited and these were disclosed (Japanese Patent Laid-Open Nos. 02-94408, 03-025904, and 03-080411.
).

Further, in Japanese Patent Application Laid-Open No. 3-025905, it was confirmed and disclosed that mixed ceramics having a composition of MgO, CaO, CoO and NiO is effective as a magnetic head substrate.

[0006]

[Problems to be Solved by the Invention] Further, JP-A-61-1
Japanese Patent Publication No. 92005 discloses a magnetic head using a substrate whose basic composition is MgO and NiO. However, there are drawbacks such as MgO having solubility in water and poor moisture resistance. Therefore, the object of the present invention is to have a coefficient of thermal expansion close to that of a vapor-deposited magnetic film structure,
It is an object of the present invention to provide a material which has a high Vickers hardness and does not cause an excessive chemical erosion reaction between other head constituent materials.

[0007]

That is, the present invention is based on CoO
As a result of further studying the additives for the basic composition of NiO and NiO, MgO was added in an amount of 0.1-10
It has been found that addition of wt% satisfies the desired properties.

That is, the present invention provides a non-magnetic substrate for a magnetic head, characterized in that CoO and NiO are used as a basic composition, and 0.1 to 10 wt% of MgO is added to 100 wt% of the composition. ..

In order to facilitate understanding of the present invention, the constitution of the present invention will be described specifically and in detail below. Basic composition is NiO
And CoO means a composite oxide, and the composition of the composite is, for example, CoO / NiO (molar ratio) = 1/99 to 80/20.
And more preferably CoO / NiO (molar ratio) = 3 /
97-60 / 40. The composition is 100 wt%, and MgO is added in an amount of 0.1 to 10 wt%. MgO is a substance that improves the sinterability because it forms a solid solution with NiO, and the addition of 0.1 wt% or more increases the density and improves the hardness and strength. In addition, the coefficient of thermal expansion is NiO, C
It is almost equivalent to oO, and the coefficient of thermal expansion can be easily adjusted.
However, if the addition amount exceeds 10 wt%, a segregation portion is generated, which is not preferable. The addition is also effective alone or in combination with the already disclosed additive. It is desirable to adopt a combination corresponding to the desired hardness and thermal expansion coefficient.

Next, a method of manufacturing the substrate will be described. Starting from each of the commercially available oxides, weighed to the desired composition,
Mix with a ball mill. Mixing is carried out, for example, in a wet ball mill in ethanol for 10 to 30 hours. CI after drying
P molding, for example, calcination in Ar at 850 to 1100 ° C.,
Then, it is crushed using a coarse crusher and sieved with a sieve of 100 to 200 μm. The calcined powder is further treated with, for example, a wet type ball mill in ethanol for 20 to 72 hours and finely pulverized to 1 μm or less. After granulating this, CIP molding is performed, for example, sintering is performed in oxygen at 1230 to 1400 ° C., and then HIP treatment is performed. HIP processing conditions are 80 to 120 MPa, 1
200-1350 degreeC and 1-2 hours are desirable.

It was confirmed that the sintered body thus obtained had a dense and rock-salt type structure, less friction due to tape sliding and chipping of the edge portion, and was superior to conventional materials. did it.

An embodiment of the present invention will be described below.

[Example 1] Using CoO and NiO as raw materials, CoO / NiO
(Mole ratio) = 35/65 was adjusted so that magnesium oxide was mixed as an additive into the composition as shown in Table 1. Mixing was carried out for 20 hours in a wet ball mill in ethanol. This mixed powder was calcined in Ar at 1000 ° C., and then pulverized with an ethanol wet ball mill for 40 hours. The crushed powder was CIP molded and then sintered in oxygen at 1350 ° C. This was subjected to HIP treatment at 1250 ° C. and 100 MPa for 1 hour. The relative density of the sintered body was a value exceeding 99%.

MgO according to this embodiment is 0.1-10 w
Table 1 shows the physical properties of the sintered body added with t%. As physical property values, the coefficient of thermal expansion (α: μm / m ° C.), Vickers hardness (Hv), and the presence or absence of segregated portions were observed.

As a comparative example, barium titanate, which is a conventional material, the physical properties of the same basic composition without addition of additives and the same basic composition with 11% by weight of additives were also shown.

[Table 1] * Is a comparative example. The coefficient of thermal expansion is almost determined by the basic composition and is 13.8 ± 0.2 μm / m ° C. in the range of this embodiment. This value is almost equivalent to that of the magnetic film structure. It is not preferable because the hardness is low when it is not added, segregation occurs when the addition amount is 11 wt%, and the hardness is too high when barium titanate, which is a conventional material, is too high and the coefficient of thermal expansion is low. .. Therefore, the addition amount of MgO is 0.1
It is necessary to make it 10 wt%.

[0015]

As described above, the present invention has the following effects. (1) The non-magnetic substrate of the present composition can obtain characteristics similar to those of the magnetic film structure in terms of coefficient of thermal expansion and hardness. For this reason, peeling of the magnetic film structure and occurrence of cracks can be significantly prevented.

(2) Further, by increasing the hardness, the life of the magnetic head can be shortened and the deformation and cracking of the non-magnetic substrate can be suppressed, and there is an advantage that the head is particularly excellent in wear resistance and durability. ..

Claims (1)

[Claims] 1. A non-magnetic substrate for a magnetic head, comprising CoO and NiO as a basic composition and adding MgO in an amount of 0.1 to 10 wt% with respect to the composition.